FSEC® Researchers Study Degradation of Current PV Module Designs

Researchers at FSEC and throughout the nation determined that the lowering costs of photovoltaic modules has not impacted their durability.

In a five-year study that began in 2016, scientists from around the nation purchased over 800 photovoltaic (PV) modules, representing seven manufacturers and 13 module types, and installed them in various climate conditions to observe their performance over time. The results show that, while plenty of opportunities still exist to extend module lifetimes and improve performance in the field, lowering the cost of PV has not affected the degradation rate of the modules.

Researchers from FSEC®, at the University of Central Florida, assisted in a five-year study to test the durability of photovoltaic modules in the hot and humid Florida climate.

Researchers Hubert Seigneur and Dylan Colvin at FSEC®, Florida’s Premier Energy Research Center at the University of Central Florida, were a part of the nationwide study to determine whether the reduced cost of PV, due to altered designs and changes in material, would result in degradation and decreased durability of the modules. The testing procedure and the results of their studies were recently described in the article, “Onymous early-life performance degradation analysis of recent photovoltaic module technologies”, which was published in Progress in Photovoltaics, a monthly peer-reviewed scientific journal covering research on photovoltaics. Following the publication of the article in Progress in Photovoltaics, PV Magazine highlighted the study as well as the published article in their own feature.

Photovoltaic modules degrade over time as they are exposed to elements. This example of a 60-year-old module shows that even after enduring the harsh Florida climate, the panels are still producing power.

The study found that module degradation rates tend to stabilize after three to four years, and that additional flash-testing after this period could help system owners better ensure that modules are performing according to expectations.

“The results of the study are encouraging for the industry,” said Seigneur. “On average, the performance degradation is on par with the typical warranty from manufacturers. Surprisingly, though, there were significant differences in performance amongst the leading manufacturers.”

Studies like this can reassure system owners that although there have been many changes to materials and designs in the past 10 years, the investment they make in photovoltaics is still beneficial.

The study was also beneficial to the research teams.

“This was a fruitful collaboration with leading scientists at the national laboratories, resulting in mutual benefits,” said Seigneur. “We were able to exchange details regarding our respective lab methods and procedures and further strengthen our respective programs. This study attests to the quality of the PV research conducted at FSEC.”

 

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U.S. Department of Energy Awards FSEC $1M Contract for Continued Efforts in EnergyPlus

Did you know that buildings account for more than 40% of U.S. total energy use and 70% of the country’s electricity use? Reducing that consumption to match renewable generation is one of the key challenges of our clean energy future, according to the U.S. Department of Energy. The need to design and operate buildings to be more efficient, flexible, and responsive is essential to help meet that challenge. This is a primary focus at the FSEC Energy Research Center, which has been awarded a $1,000,000 contract for continued efforts in the Department of Energy’s flagship whole-building energy simulation software engine, EnergyPlus.

EnergyPlus is an open-source, whole-building energy simulation software that engineers, architects, and researchers use to model both energy consumption—for heating, cooling, ventilation, lighting and plug and process loads—and water use in buildings.

FSEC ERC has decades of whole-building energy simulation program development experience and has been part of the Department of Energy’s EnergyPlus core development team since 2001, when the Department of Energy changed from the DOE2.1 simulation program to EnergyPlus. Since then, FSEC ERC has been one of many central teams working with DOE’s National Renewable Energy Laboratory, to maintain, research, and develop the simulation program.

FSEC ERC is an essential part of the bi-annual updates for the program every year, not only providing software updates and fixing glitches, but also writing and creating new software within the program.

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Metrics for Energy Efficient Buildings: How Do We Measure Efficiency?

efficiency level conceptual meter indicates 100 percent, isolated on white background
When it comes to an entire house or building, or comparing homes or buildings, what should the measurement be?

Some measurements are very direct like the height cleared by the Olympic high jumping gold medalist this summer. Efficiency has a number of nuances, though, that make measuring it difficult in terms that allow consumers to make informed decisions. When it comes to an entire house or building, or comparing homes or buildings, what should the measurement be? And how should you compare energy use on-site versus off-site? How do you determine what is efficient about the building versus the operations of the building? And how should renewable energy use or the time of energy use, and time-dependent cost of energy use factor in? Should the emissions of the source of the energy used be factored? To learn more, read the paper written by FSEC’s Deputy Director Philip Fairey and Natural Resources Defense Council’s David Goldstein.

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Metrics for Energy Efficient Buildings: How Do We Measure Efficiency?*

 

*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA in August  2016.

Can a Water Heater Help Cool Your House?

Heat pump water heater inside laundry room of house, photo.
Heat pump water heaters were tested in the lab and in the field.

Most electric water heaters use an electric resistant rod in the tank. But there is another option for electric water heaters – one that is familiar to most Floridians, and that is a dedicated heat pump for heating hot water. Just like a regular heat pump for heating the air in your house, the heat pump water heater has a small compressor unit on top that uses vapor compression to heat the water. Prior FSEC research on heat pump water heaters (HPWH) in Florida showed that they saved approximately 66% of the energy needed to heat water with an electric resistance system. HPWHs also create a quantity of cooled, dehumidified air from the compressor section of the unit as a by-product of their operation. FSEC researchers found out that a HPWH coupled to the conditioned living space can reduce space-conditioning energy in a cooling-dominated climate, but with qualifications a lab test was undertaken to investigate the effect of coupling a garage located HPWH to the conditioned space with ductwork. With the HPWH ducted to and from the interior, cooling energy dropped by 4% or 0.8 kWh/day. Effect on space heating energy for this configuration could not be determined. Experiments also investigated using an outdoor air source for the HPWH, to supplement ventilation. During the cooling season, the HPWH tempered the outdoor air with only a minimal impact on cooling energy. Space heating energy increased by 18% or 1.4 kWh/d. The space coupling of the HPWH had a minimal impact on water heating efficiency.

In later field evaluation, eight occupied homes were retrofitted with a HPWH coupled to the conditioned space. Results were more pronounced than the lab evaluation: cooling energy savings averaged 8% (1.1 kWh/day). Space heating energy use increased by 24%, although with considerable variation and little application in Florida’s mild climate. The evaluation suggested the coupling eroded some of the HPWH water heating energy use savings, reducing it by 0.4 kWh/day or 11%. If not located in the house, you often end up with a slightly cooler garage.

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Measured Performance of Ducted and Space-Coupled Heat Pump Water Heaters in a Cooling Dominated Climate*

 

*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

Getting to a Near-Zero Energy Existing Home

Rear view of house with screened in back porch and solar electric array with 36 panels on roof
Near-zero energy use home after deep energy retrofits.

Monitoring results over a four-year period document a phased retrofit applied to a central Florida home with very high electricity consumption, eventually ending in a home with near-zero energy use. The retrofit included simple pass-through measures, such as the installation of efficient lighting and low-flow shower heads, as well as deeper measures which included a high-efficiency space heating and space cooling controlled by a smart thermostat, a heat pump water heater, and ENERGY STAR® appliances. The average household electricity use was reduced through a combination of these efficiency measures and photovoltaic power generation by 82%. Results from the case study, and nine other deep retrofits suggest how an effective zero-energy home (ZEH) program can be implemented in otherwise poorly performing existing homes.

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From Energy Guzzler to Near-Zero Energy Home: Lessons from the Phased Deep Retrofit Project

*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.